Various devices and methods for measuring measurement objects are known from the prior art. Coordinate measuring machines have tactile sensors which probe a surface of the measurement object, for example mechanically. Tactile sensors of this type typically have a probing element in the form of a probe ball that is secured to a transmission element. During probing by the probe ball with the measurement object, forces that arise on the probe ball are measured in three axes and a direction vector of the probing, the so-called probing vector, is determined therefrom and the measurement object is thus measured.
Devices having optical sensors, in particular coordinate measuring machines having an optical measuring head or measurement microscopes, are furthermore known. Devices of this type are configured to measure the measurement object in a non-contact manner. By way of example, DE 101 11 130 A1 describes a coordinate measuring machine including a video probe head that is displaceable in the coordinate directions (x, y, z) by way of a mechanism and a control and evaluation unit for processing the measurement values and for controlling the mechanism. The advance data are derived from the image data of the video probe head in order to be able to displace the video probe head in automated fashion along the contour of a workpiece with an unknown workpiece contour.
Features of the measurement object can be measured using coordinate measuring machines including measuring probe heads. In optically expanded coordinate measuring machines, further features that are not measurable in tactile fashion, for example because these cannot be probed mechanically, can be measured by a camera. Examples of these features are prints on a workpiece, soft materials or transitions of composite materials, which can only be distinguished optically. However, other measurement objects cannot be measured optically as they are only accessible with a stylus, such as deep bores, for example. Moreover, capturing a Z-component (height) with a sufficient accuracy may not be possible in the case of an optical measurement as the Z-component can only be established approximately by way of focusing.